It is known to use air-drying alkyd resins having high acid numbers for the production of aqueous lacquers and other film-forming agents. Such alkyd resins, having high acid numbers, have good water solubility in the form of their amine salts. Such alkyd resins and film-forming systems based thereon, have the disadvantages of unsatisfactory resistance to water and water vapor, and require considerable amounts of volatile amines and solvents for satisfactory dispersion. While drying and curing, the film layers formed from such high acid number resins release the amines and solvents. Such amines and solvents are undesirable sources of pollution to the adjacent atmosphere. To reduce such pollution it is often necessary to carry out the curing steps in specially designed apparatus to trap or recover these toxic substances. Such apparatus is expensive and the cost of such apparatus often overshadows any savings from the recovered solvents.
It is also known to modify film-forming materials by the incorporation of hydrophilic groups, particularly, polyethylene glycol chains into the resin molecule so that self-emulsifying alkyd resins or melamine resins result. It is also known that even without direct incorporation into the resin molecule, it is possible to use the adducts of ethylene oxide with some fatty alcohols, as low molecular weight, nonionic emulsifiers. In such cases, however, portions of a hydrophilic radical remain active in the film. The resultant films are susceptible to water penetration. A marked reduction in the hardness of the resultant film is also noted.